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I06. COMPOSITIONS,

-, j r regular clearage planes and line fracture. When broken anprep-atlas COATING OR PLASTIC.

UNIT sT T sPATENT om." t. I

JAMES H. DRAKE, on ST. PAUL, MINNESOTA, AND DA Vl'D c. .wEnMsfoF VCHICAGO, ILLINOIS.

- SPECIFICATION forming part of Letters-Patent No. 273,824, M 13, 1 883.

Application filed December 8, 1882. lNo specimens) 5 of Uook,-StateofIllinois, havejointly invented certain new and useful Improvements inComposite Stone; and we do hereby declare the following to be afullfiiear, and exact dscrip tion of the invention, sufficient to enableothers l0 skilled in the art to make and use the same.

Our invention relates to composite stone, or, in other words, to stoneformed artificially by h "draulic cem t with other suit I materia s, reucing e same 0 p astic condim water or aqueous solutions, molding intosuitable forms or blocks and thereafter curin as is we um ers 0 din theart.'

The present invention is based upon the dis- .covery of thepeculiarqualities of a natural stone mentioned in the Reports of the UnitedStates Geological Surveys as gnartzite 99k, occurring in southern Dakotaan southwestern Minnesota. This gnartzileis found more particularly atSioux F'alls,Minnehaha county, 2 5 Dakota, where it outcrops inregularbed and is generally known as Sioux Fall This stone as it occurs innature is remarkably hard and impossible toivork by any of the usualtools, however finely tempered. It has hereinafter described, theresulting com e stone, havingthesaid Sioux Falls quartzite r as aningredient, presents a close, firm, even 5 texture, is susceptible ofthe highest polish, and is W0 that it is only with exceeding di cultythat it can be scratched,

' chipped,stained,broken,or otherwise marred, being, in short,practically indestructible.

40 The composite is therefore of especial value in making tilestessellated fiQQMLLaXB- ments, co erslaiisfwai nscoting, washand-in-manyother relations where marbles or other polished natural stones orvitreous tiles are now employed,

but which, being less durable, much sooner deteriorate under roughusage. The composite stone may also be used as a building-block, and, ifpreferred, be left oli'shedrits-fin'e- 5o ness of grain and slightfen'ency to absorb moisture enablin it to withs V rosts a re same time t atits tenacity and I one part of hydraulic cement, En I sIi Port-1 landeing pre erre SufictenE-gft e Sioux Falls stone is to be reduced to con-6o be polished in any well-known manner, prefin conjunction with or tohe entire exclusion roe coM oslTs STONE. t

hardness cause it to resist the st crush- I K ing strains.

In the practice of a the invention, we take 5 5 from four to eightparts, by measure, of the broken ant u verized SiouxFalIs stone todition ofa fin )owder b b y g, or other convenien means, so thatinsuchcon may 1 lwisand or the like in uniting the materials together. The

remainder of the stonema y be ll))I0Il9I1 to tabout pea-size, althoughsomemay e eft o nu Md this is to be preferred when him ished stone it isdesired to produce mosaic ef.-- fects on the surface. In such event thenut- I size of stone will be so disposed in the plastic 7o j mass as tocome next to the surface of'the fin-f ished block. The cement andbrokemand pulverized Sioux Falls stone are intimately mixed togetherwith a. quantity of water with cient to reduce the mass to aplasticcondition, after which the same may be cast in molds and allowed toremain until set, as well understood in the art. When the"form f is yetgreen, and after it has been removed from the mold it is preferred thatthe surlace thereof should be coated with a slip consisting of thefinely-pulverized Sioux Falls, stone,

thinned with water or with an aqueous solotion of sod' to or the like,the-excess of r the slip eing care ully scraped away,so as to v I leavethe cast of even surface. During several days thereafter theIgreen'castis *kept moistenedwith water, and mav be carbonated in a close chamberor subjectet to rec-air exposure to indurate the same as desired. When osnfiiciently hardened the composite stone may erably by use of an emeryor corundum wheel f with water and fine-powdered Sioux Falls stone as an:abrader; or a rubbing-bed of 5 Sioux Falls stone in natural conditionmay be? employed with said powdered stone as an abrader, as beforestated. It will be understood th t sand may be used of the pulverizedSioux Falls stone as a binder in the composite, although we have foundthe best results to ensue when said pulverized stone is used alone, asheretofore described, for it is plain that in such condition itefi'ectually fills the pores of the block, and being of like qualitywith the broken stone makes the cast of homogeneous texture, and causesthe polish to be uniform and highly elTective. Moreover, it seems insuch condition to unite with cement much more closely than if it wereordinary sand, thus serving to hold the broken stone firmly in place sothat no loosening thereof or of the binder next its irregular edges isnoticeable upon polishing the finished block. This peculiarity of thepulverized stone in its relation as a binder enables the composite blockto resist weathering to the utmost, at the same time, if it be polished,to preserve the finish without flaking, chipping, or like deterioration.

In lieu of water, an aqueous solution of sodic silicate or some suchchemical com-pound well known and in common use for the purpose may beemployed to reduce the mass to plastic condition suitable for molding,as described, and, if desired, any of the well-known mineral pigments tovary the color of the composite stone may be incorporated, although itpossesses of itself a reddish tint not unlike.

Tennessee marble or Scotch granite when polished, which for mostpurposes it may be preferred to retain.

What we claim as new, and desire to secure by Letters Patent, is-

1. A composite, stone having uart or Sioux Falls stone as a principalingredient thereof, substantially as specified.

2. A composite stone consisting principally of quartzite or Sioux Fallsstone united with hydraulic cement and polished, substantially-

